Area Forecast Discussion
Issued by NWS Green Bay, WI
Issued by NWS Green Bay, WI
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244 FXUS63 KGRB 292108 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 408 PM CDT Mon Apr 29 2024 Forecast discussion for routine afternoon forecast issuance .KEY MESSAGES... - Scattered showers in east-central and far northeast WI will come to an end early this evening. A few rumbles of thunder are possible. - Due to recent rainfall, rivers and streams will be on the rise through midweek, with a few of them possibly reaching bankfull stage. - Dense fog is possible over the bay and lake mainly north of Sturgeon Bay through early this evening. - There is a chance of showers and a few thunderstorms Tuesday night. Additional rain and thunderstorm chances are possible at times from late Wednesday night through Friday. && .DISCUSSION... Issued at 407 PM CDT Mon Apr 29 2024 Short Term...Tonight and Tuesday As a surface low gradually tracked northeast from southeastern MN into northwest WI this afternoon, a line of scattered showers developed along its occluded front over eastern WI early this afternoon. Embedded thunderstorm development had not been observed despite a couple hundred of elevated instability analyzed this afternoon. The lack in thunder could be a result of a lack of mid- level moisture, too weak of instability, and low mid-level lapse rates. Therefore, the chance of thunderstorms developing for the remainder of the evening remains very low. As the surface low continues to track into Upper MI into this evening, the line of scattered showers will exit the forecast area to the east/northeast. For the remainder of the night, the mid-level shortwave associated with the surface low will shift overhead. Forecast soundings indicate enough low-level moisture in central WI and across the Northwoods to generate low clouds through Tuesday morning. A few sprinkles may accompany the low clouds through late this evening with potential for fog to redevelop later tonight through early Tuesday morning. Ridging will follow the shortwave for Tuesday, allowing clouds to decrease for the return of some sunshine. The timing of the ridging has slowed slightly from the previous forecast, causing the warmer air to reach the area a little slower. Therefore, lowered Tuesday`s highs by a few degrees. Still anticipate highs mainly in the 60s, but have removed the 70s from the southern portion of the forecast area. Long Term...Tuesday Night Through Monday A mid level PV anomaly and attendant trough will bring showers and thunderstorms to northeast Wisconsin Tuesday night as this feature tracks through the western Great Lakes region. This feature should mainly be out of the region by Wednesday morning, with some showers possibly lingering across far northern Wisconsin Wednesday afternoon. Wednesday is expected to be dry, warm, and breezy behind the departing low. These conditions could cause some fire weather concerns as relative humidity values plunge along with the gusty winds and warm afternoon temperatures. The main factor that may prevent elevated fire weather conditions will be the rain on Tuesday night and the relatively short period these conditions are expected given more precipitation is expected later in the week. A well organized low pressure system emerging over the central Plains will lift northeast towards the upper Mississippi Valley on Thursday then the northwestern Great Lakes region Thursday night. This system will bring a prolonged period of showers and thunderstorms at times from late Wednesday night through Friday. The prolonged period of precipitation will keep temperatures cooler than earlier in the week; however, temperatures will still be around or slightly warmer than normal for this time of year. The prolonged precipitation will also bring flooding concerns as area rivers have risen a bit from this weekends event, with an additional period of rain causing area rivers to reach bankfull, depending on how much rain falls and where later this week. The models this weekend indicate there will be another period of rain at some point, but at different intensities. The GFS/Canadian have precipitation Saturday and Saturday night, with a bit more QPF and a stronger low pressure system. The ECMWF indicates a much weaker low with a paltry amount of QPF on Saturday. AFter the weekend, the ECMWF brings another low pressure system with a healthy amount of rain on Monday while the GFS/Canadian are dry with a high pressure system across the Great Lakes. Given the model differences will stick with the NBM in that portion of the forecast as things are still up in the air. && .AVIATION...for 18Z TAF Issuance Issued at 101 PM CDT Mon Apr 29 2024 A warm front has slowly been lifting north during the late morning, reaching AUW/CWA and GRB as of early this afternoon. LIFR conditions existed to the north of this front with cigs between 200 and 600 ft AGL, isolated rain showers, and reduced vsbys from the rain and patchy fog. South of the front, MVFR and VFR conditions prevailed. The warm front will slow its trek north this afternoon as the system`s cold front moves across the region from the southwest. As this is occurring, scattered rain showers will develop. A few thunderstorms are also possible, with the best chance over the east-central WI TAF sites between 19z and 22z. Cigs will lower back to IFR/LIFR late this evening and overnight across the central and north-central WI TAF sites with the potential for fog or sprinkles to redevelop. Meanwhile, VFR conditions will prevail across the east-central WI TAF sites. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Kruk/Kurimski AVIATION.......Kruk